Heterosexual African HIV-1 serodiscordant couples (i.e., one member is HIV-1 infected and the other uninfected) face high risk of HIV-1 transmission and are a priority population for implementing new HIV-1 prevention interventions, given their risk, ability to be targeted for prevention through couples HIV-1 testing, and advantage to the partnership to avert HIV-1 transmission. Robust evidence-based HIV-1 prevention strategies are available for couples, including two powerful interventions that demonstrated high efficacy in clinical trials among couples: antiretroviral therapy (ART) and pre-exposure prophylaxis (PrEP). During the current funding cycle of this grant, we conducted high-impact, multidisciplinary work, including novel epidemiologic analyses, mathematical modeling, and social, behavioral, and implementation science to: a) define effective and cost-effective approaches to prioritize delivery of antiretroviral-based prevention to highest- risk couples, b) understand user preferences and facilitators/barriers to use of both ART and PrEP for prevention in this population, and c) pilot an optimized combination prevention package integrating ART and PrEP in a demonstration study among 1000 African couples at four HIV-1 research centers (the Partners Demonstration Project). PrEP and ART were integrated as a package, with PrEP offered prior to ART initiation, including when ART was delayed or declined, and then during the first 6 months after ART start, while achieving viral suppression; we called this the PrEP as a bridge to ART strategy. This intervention resulted in a 96% estimated reduction in HIV-1 transmission. Translating this success to full-scale delivery is needed to move this work to implementation impact. In Kenya, the Ministry of Health has developed an ambitious HIV Prevention Revolution Road Map 2030, in which moving combination biomedical and behavioral prevention interventions for key populations into delivery settings is defined as a national priority. We have assembled a multidisciplinary team, including the Kenya Ministry of Health, to advance pragmatic delivery of ART and PrEP for this key population. We propose to utilize the RE-AIM (Reach, Effectiveness, Adoption, Implementation, and Maintenance) implementation science framework to guide roll-out of PrEP as a bridge to ART for HIV-1 serodiscordant couples in Kenya. We will implement a stepped-wedge trial design to randomly assign 18 HIV-1 care centers to scaled implementation of our PrEP as a bridge to ART strategy. Our Aims are to evaluate program impact; assess facilitators and barriers to implementation at the health system, organizational, provider, dyadic, and individual levels; and cost and cost-effectiveness of integrated delivery of PrEP and ART.